Reticulated orthopaedic element to exploit the medullary canal of the long bones

ABSTRACT

Element for osteosynthesis including a central part or stem and two end parts. The two end parts have a proximal end and a distal end. The two end parts are comprised of a reticulate of titanium or other biocompatible material which is used to exploit the medullary canal of the bones. The proximal end may be temporarily coupled to an introduction instrument. The meshes of the reticulate allow for screwing of at least one transverse screw.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to reticulated orthopaedic elements toexploit the medullary canal of the long bones.

More particularly, the invention concerns an element of the abovementioned kind, totally or partially reticulate, that, in order to beapplied and transversely blocked, allows to operate without employingray apparatuses.

As it is well known, every bone is modelled, as far as shape and massare concerned, to satisfy to the particular mechanical necessity for thespecific situation in the skeleton.

At the skeleton functional level, the bones satisfy the static andlocomotion necessity. With respect to the shape, bones are divided intocategories, e.g. long bones, bones having a mainly cylindrical extensionwith respect to the diameter, flat bones and short bones.

The long bones have an extended body, called diaphysis, and have twoterminal ends, more or less broadened, called epiphysis. The long bonesat the diaphysial level, if seen along a sagittal section, or by aradiographic examination, have a long and large lumen called medullarycanal, surrounded by an osseous compact casing. At the epiphysial levelthe long bone has spongy osseous zones.

Objects of the present invention include that of finding a newapplication technique for the reparation and rehabilitation of traumasof long bones and of articulations, exploiting the medullary canal asbearing and support either of the prosthetic manufacture for thereparation and of the arthro-prosthetic manufacture.

2. Description of the Prior Art

At present, the orthopaedic prostheses can be classified as a)endoprostheses, arthro-prostheses (hip joint, knee, elbow,humero-shoulder prostheses, etc.): where to replace one or both of thearticulation heads is replaced with a metal prosthesis; b) revisionendoprostheses arthro-prostheses (hip joint, knee, elbow,humero-shoulder prostheses, etc.): wherein the second or subsequentintervention after the failure of the preceding prosthesis, only one orboth of the articulation heads is replaced with a metal prosthesis.

There are also the trauma prostheses for long bones used to obtain theendomedullary osteosynthesis.

In the prostheses for the articulations, the prosthetic stem isintroduced by friction within the lumen of the medullary canal to obtaina immediate primary stability.

Often, lacking this primary stability, an "orthopaedic cement" is usedin order to compensate the lacking of precision in the coupling betweenthe prosthetic stem and the medullary lumen: in this way an immediatestability is obtained, but afterwards great problems for the osseousresorption are present: in some cases even the loss of the prostheticmanufacture can occur.

The osteosynthesis technique provides the union of two or more fracturedbone segments by metallic parts.

An endomedullary nail is defined as the osteosynthesis elementexploiting the endomedullary lumen of the long bones. It is indicated asa locked nail, an endomedullary nail crossed by transverse or diagonalscrews in correspondence of its distal and proximal ends.

EP-A-0268115 describes an element for osteosynthesis made up of areticulate of titanium or other biocompatible material.

At present, all the endomedullary nail requires for the distal lockingis the use of the image intensifier and/or other apparatuses irradiatingionizing rays during their application.

The main drawback that the present invention aims to solve is that ofavoiding the necessity of using the above apparatuses to transverselyintroduce and lock the abovementioned implants.

SUMMARY OF THE INVENTION

Particularly, the innovative solution according to the inventionconsists in the exploitation of the bearing and the support of thearthro-prosthesis, of the revision arthro-prosthesis or of theendomedullary nail, of the endomedullary lumen by a reticulate metallicstructure made up by titanium or another biocompatible material thatassumes the shape and the total or partial length of the medullarylumen.

The tubular reticulate shape allows to obtain a transverse anchoring ineach point chosen by the operator to apply a transverse screw/clip/wirewithout the necessity of any control by an irradiant diagnosticapparatuses.

Simply, using the suitable mill a hole is realized. The mill in eachspatial position will center a mesh of the reticulate and will allow toscrew the transverse screw.

With all of the systems now available there is an unavoidable necessityuse the ray apparatus. The surgeon must find the preholed seat on theprosthetic manufacture by the image of the intensifier and then mill inthe corresponding point through the bone to realize the transverselocking.

As it is well known, the simple endomedullary nail alone cannotguarantee the control of rotations and cannot maintain the length of thebone in case of metaphyseal fractures and in case of plurifragmentaryfractures. The traditional locked nail solves both the situations, butit is absolutely necessary to introduce and lock it to use the imageintensifier.

On the contrary, an endomedullary nail realized according to thetechnical teachings according to the invention permits one to immobilizethe complex diaphysial fractures transverse locked in every suitableposition without the use of a ray and in a simple and sure way.

A reticulated endomedullary nail realized according to the inventionallows the stabilization from static into dynamic, is able to promotethe axial stresses on the focus thanks to the load, thus obtaining anoptimum stiffening.

The solution proposed according to the present invention yields a widepossibilities of applications for the treatment of the fractures of thelong bones since it can be produced with every length and diameter thatvaries with the varying of the different ratios medullary lumen/osseousdiameter in the various anatomical zones (femur, shinbone, humerus,radium, cubitus, etc.).

The solution according to the invention enables one to make thetreatment of the subtrochanteric fractures, of the fractures of thetertius distal, of the multiple, spiroidol and segmental fractures, ofthe comminuted fractures, of the fractures involving the loss of theosseous substance, of the pathologic fractures, of the pseudarthrosis,of the defective consolidations, of the elongation and shorteningosteotomias, of the osteosynthesis in closed air.

Still according to the invention, it is possible to transform all theendomedullary nails and the primal arthroprosthesis and/or revisionendomedullary stems in reticulate stems, increasing the contact surfaceprosthesis-bone so that a better primary and secondary coupling areobtained.

Further, according to the invention, a special advantage is obtained byeliminating the orthopaedic cement.

A further advantage is that of having the opportunity of obtaining amanufacture remarkably lighter than the prosthetic manufacture alreadyavailable. The reticulate in the distal or proximal ends permits themost suitable transverse/diagonal/sagittal/oblique locking without thenecessity of using a specific instrument or irradiating diagnosticapparatuses and thus guaranteeing to the patient a better primary andsecondary stability.

It is therefore a specific object of the present invention that areticulate orthopaedic element characterized in that it is comprised ofa central part or stem and of two ends parts, namely a proximal end, adistal end part, in that at least said two end, pads are made up of areticulate of titanium or other biocompatible material, in that it isused to exploit the medullary canal of the bones, in that the proximalend is provided with coupling means, for temporary coupling with anintroduction instrument, and in that the meshes of the reticulate allowthe screwing of at least a transverse screw.

Particularly, according to the invention, said element can be completelyreticulate.

Still according to the invention, the element is made up as a uniquepiece, or by separated connectable parts.

In case the element according to the invention is made up of connectableparts, the connections are realized by male-female threads and/or welds,or other kind of fixed joints.

In order to allow the easy removal from the patient of the elementaccording to the invention, said reticulate parts can be covered with asheath made up of biocompatible plastics, e.g. Teflon®,(tetrafluoroethylene (TFE)) polyethylene, or a biocompatible thinlamina. In this case, the transverse locking is to be consideredindispensable to increase the stability of the element.

Obviously, the dimensions, the thickness, the diameter and the meshes ofthe reticulation vary in function of the specific application, of thekind of operation and of the patient.

Further, according to the invention, particularly in case of therealization of endomedullary nails, said prosthesis will be realizedinnerly hollow, and provided with longitudinal grooves along all or partof the extension of the prosthesis. The grooves increase the elasticityand the flexibility of the element according to the invention, makingeasier both the insertion and the removal of the same.

In a preferred embodiment of the reticulate element according to theinvention, it is realized in three parts, the central one beingnon-reticulate and having variable length and diameter, and the end onesbeing reticulate, standardized, and connectable with each kind ofcentral part employed.

Further, according to the invention, the proximal end of the reticulatecan be provided with male or female mechanical coupling means, for thetemporary coupling with the introduction instrument.

When a prosthesis for the collum femoris is realized, the stem part ofthe prosthesis that is introduced within the medullary canal of thediaphysis is made up of a very strong reticulated part that allows toabsorb the stem, to increase the contact surface for the osteosynthesis,and to have the opportunity of transverse blocking, this opportunity notexisting with the prior art solutions.

The reticulate according to the invention will preferably have athickness in the range between 0.05 mm and 7.0 mm.

Further, it can be made with a closely-woven weft, an open weft, or witha crossed weft.

The elements according to the invention can have any tridimensionalshape which is desired, e.g. undulated, pressed, with a loosen mesh,electrowelded, with a square or rectangular mesh, S-shaped, V-shaped,O-shaped, with a right or left spiral mesh, with a plate bent at anangle between 5° and 90°, with an expanded metal, etc.

The wire constituting the reticulate can have any shape, also ifobserved in section.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be now described, in an illustrative and notlimitative way, according to its preferred embodiments, with particularreference to the figures of the enclosed drawings, wherein:

FIG. 1 shows a preferred embodiment of an endomedullary nail accordingto the invention;

FIG. 2 shows a particular of the nail of FIG. 1;

FIG. 3 shows the application of the nail according to FIGS. 1 and 2;

FIG. 4 is a diagrammatic view of a hip joint prosthesis according to theinvention;

FIG. 5 is a diagrammatic view of a revision hip joint prosthesisaccording to the invention;

FIG. 6 is a diagrammatic view of a knee prosthesis according to theinvention;

FIG. 7 diagrammatically shows a different shape of a stem for a kneeprosthesis according to FIG. 6;

FIG. 8 shows the prosthesis of FIG. 6 in place;

FIG. 9 is a diagrammatic view of a revision knee prosthesis according tothe invention;

FIG. 10 shows the prosthesis of FIG. 9 in place;

FIG. 11 is a diagrammatic view of a humero-scapular prosthesis accordingto the invention; and

FIG. 12 is a diagrammatic view of an elbow prosthesis according to theinvention.

The nail 1 of FIG. 1 has a central stem 2 and two end parts 3.

Being an endomedullary prosthesis, both the stem 2 and the end parts 3will be centrally hollow.

The three parts 2 and 3 are coupled to each other, see particularly FIG.2, by a thread 4, that obviously can be replaced by any other kind ofstandard coupling.

The two end parts 3 are realized by a titanium reticulate, even if adifferent suitable material can be used.

The meshes of the reticulation will obviously vary in function of thespecific application of the prosthesis.

For example, in case of an adult of remarkable dimensions, it can have astem having a diameter of 16 mm, wire of the reticulation having adiameter of 2.5 mm and meshes having a side comprised between 2 and 6mm, while in case of a child, the stem can have a thickness of 10 mm,the wire of the mesh a thickness of 0.5 mm and the meshes a side of 2-3mm.

As it can be particularly seen in FIG. 2, the reticulate parts 3 arecovered with a sheath 4 realized with a biocompatible plastic material,that avoids the direct contact between bone and reticulate, easing theremoval at the end of the treatment.

At the proximal end of the reticulate part 3 a coupling 5 is providedfor a plug 6, that allows the coupling with the insertion instrument forthe prosthesis, or with centering or measuring instruments.

Coming now to observe the FIG. 3, the application of the transverseself-threading screws 7 that are introduced through the reticulate part3, previously drilled by a mill can be observed.

The transverse locking on both the ends allows to neutralize the torsionstresses, and to maintain the same length of the segment.

Coming back to observe FIG. 1, it can be noted the global composition ofthe endomedullary nail realized according to the teachings of thepresent invention, placed within the fractured femoral medullary lumen.

The transverse locking is realized without employing the imageintensifier since the orthopaedic surgeon knows that in a zonecorresponding to the end parts 3 is in any case possible to realize thehole by the mill, and therefore it is sufficient that the mill centersthe parts 3 to have a hole useful for the transverse locking.

Coming now to particularly see FIGS. 4 and 5, and beginning from theFIG. 4, it is shown a hip joint prosthesis 8. It has a reticulate stem 9that allows to obtain the following advantages with respect to thealready known systems:

application of the prosthesis with the growing of the medullary bonewithin the medullary lumen in the reticulation of the implant stem witha remarkable increasing of the prosthetic stability, and of theosseous-implant contact surface;

it can be avoided the use of the orthopaedic cement, and its seriousdrawbacks;

it can be transversely blocked the hip joint prosthesis to thesurrounding bone by the transverse fixing screws 10, without employingirradiant, diagnostic apparatuses;

the shape and the length of the reticulate stem and the shape and thethickness of the reticulation can vary according to the specificclinical and operative necessities;

by the cemented or not cemented prosthetic stem a primary stability ofvery high quality is obtained, and moreover a secondary stability havingan unusual osseous-implant contact ratio is obtained.

In FIG. 5 a revision hip joint prosthesis 11 is shown: it is necessarysince with the development of the clinical experience with respect tothe application of the cemented or not cemented hip joint prostheses, anoticeable number of patients that after a certain period has clinicalproblems requiring the removal of the implant has been noticed. The lostof the implant has also the consequence that the surrounding bone isdamaged and is compromised in such a way not to be more able to sustainthe static/dynamic load of the patient and/or not to be more possible tobe a suitable seat for the new implant. To this compensation of the lossof the surrounding bone, the invention asks the total or partialexploiting of the femoral medullary lumen applying a long stem 12transversely locked by the transverse screws 13.

The advantages obtained are those already mentioned herein before.Moreover, a further increasing of the prosthetic stability and astructural compensation for the bone are obtained as a consequence ofthe lost of the implant.

Coming now to observe FIGS. 6-8, a knee joint prosthesis 14 is shown.

In the prosthetic articulation of the knee, the longitudinal verticalpart that is introduced in the femoral medullary lumen and in the tibialmedullary lumen is realized by a tubular reticulate cylinder 15: in thisway higher primary and secondary stability are guaranteed, with theopportunity and the easy ease of transversely locking the prosthesis 14without image intensifier by the screws 16.

In FIG. 7 a stem 15' is shown having different shape and length.

It can also be realized a revision prosthesis 17 (see FIGS. 9 and 10),introducing a reticulate tubular cylindrical stem 18 longer than themain stem so that it is possible to compensate the osseous lost and tonoticeably increase the ratio between the support osseous surface andthe reticulate surface of the stem, either the tibial or the femoralstem or both.

Further, since the stem is reticulate, it is possible the transverselocking of the same in every point of its extension by transverse screw19.

Coming now to observe FIG. 11, a humero-scapular prosthesis 20 is showncomprising a reticulate stem 21 introduced within a medullary lumen,allowing thus the transverse locking of the prosthetic manufacture bythe screw 22 and further to lighten in a conclusive manner the weight ofthe prosthetic manufacture.

Finally, observing FIG. 12, an elbow-humero-cubitus prosthesis 23 isshown providing a reticulate humero stem 24 and a reticulate cubitusstem 25 allowing a best performance and prosthetic stability withrespect to the traction and rotation movements ahead and backwardstressing the elbow articulation.

Both the stem 24 and the stem 25 are fixed by the screws 26 and 27.

The present invention has been described in an illustrative and notlimitative way, according to its preferred embodiments, but it is to beunderstood that changes and/or modifications can be introduced by thoseskilled in the art without departing from the scope of the invention asdefined by the enclosed claims.

I claim:
 1. Element for osteosynthesis comprising a central part and two end parts, the two end parts include a proximal end and a distal end part, such that said two end parts are comprised of a reticulate of titanium or other biocompatible material which is used to exploit the medullary canal of the bones, said proximal end is provided with coupling means, for temporary coupling to an introduction instrument, and wherein the meshes of the reticulate allow the screwing of at least a transverse screw, wherein said reticulate parts are covered with a sheath of biocompatible plastics, selected from the group consisting essentially of polytetrafluoroethylene or polyethylene, or a biocompatible metal, or thin titanium lamina, such that the sheet prevents a bond between the bone tissue and screw and such that said element may be introduced into a patient without the use of an image intensifier.
 2. Element for osteosynthesis according to claim 1, wherein said element is completely reticulated.
 3. Element for osteosynthesis according to claim 1, wherein said element is made up as one piece.
 4. Element for osteosynthesis according to claim 1, wherein said element is made of separated connectable parts.
 5. Element for osteosynthesis according to claim 4, wherein said connectable parts are coupled by male-female threads, welds, or other kind of fixed joints.
 6. Element for osteosynthesis according to claim 1, wherein said element is innerly hollow.
 7. Element for osteosynthesis according to claim 6, wherein said element is provided with longitudinal grooves.
 8. Element for osteosynthesis according to claim 1, wherein said element is comprised of three parts, the central one being non-reticulate and having variable length and thickness; the end parts being reticulate and standardized, and connectable with said central part.
 9. Element for osteosynthesis according to claim 1, wherein the proximal end of the reticulate is provided with male or female mechanical coupling means for the temporary coupling to the introduction instrument.
 10. Element for osteosynthesis according to claim 1, wherein the reticulate has a thickness in the range between 0.05 mm and 7.0 mm.
 11. Element for osteosynthesis according to claim 1, wherein said reticulate is made with a closely-woven weft or open weft, or with a crossed weft.
 12. Element for osteosynthesis according to claim 1, wherein said element is used as an endomedullary nail.
 13. Element for osteosynthesis according to claim 1, wherein said element is used as a hip joint prosthesis.
 14. Element for osteosynthesis according to claim 1, wherein said element is used as a revision hip joint prosthesis.
 15. Element for osteosynthesis according to claim 1, wherein said element is used as a knee prosthesis.
 16. Element for osteosynthesis according to claim 1, wherein said element is used as a revision knee prosthesis.
 17. Element for osteosynthesis according to claim 1, wherein said element is used as a scapolo-humero prosthesis.
 18. Element for osteosynthesis according to claim 1, wherein said element is used as a revision scapolo-humero prosthesis.
 19. Element for osteosynthesis according to claim 1, wherein said element is used as an elbow (humero-cubitus) prosthesis.
 20. Element for osteosynthesis according to claim 1, wherein said element is used as a revision elbow (humero-cubitus) prosthesis. 